| Summary: | 碩士 === 國立屏東科技大學 === 食品科學系 === 92 === The purposes of this study were aimed to increase population of mold adding starch on tofu. Molded rice tofu that had characteristic rice aroma and nutrient was developed and measured its quality. Four different proportions of starch additive (mixtures of indica rice flour/cassava starch ratios were 0: 15, 6: 9, 9: 6 and 15: 0, w/w basis) were added in soymilk to reach 15% total soymilk weight. In addition, 0.3% glucono-δ-lactone and 1% salt were also added in soymilk to produce rice tofu then inoculated with Actinomucor taiwanensis and incubated for 48 hours (28℃, RH 97%) to form molded rice tofu. Molded rice tofu was dry salted in 10% (w/w) salt for 8 hours and blanched with steam to obtain final sample.
In comparing physical properties of indica rice flour and cassava starch, to solubility and swelling, cassava starches were higher than indica rice flour whereas in water binding capacity, indica rice flour was higher. Comparing molded rice tofu trials and the control after blanching, results showed that the moisture content and water activity of molded rice tofu were decreased because of 15% starch was added. The moisture content and water activity of all the molded rice tofu trials were below 67% and 0.9 after blanching, respectively. The pH values of molded rice tofu trials were between 5.87 ~ 6.00 after blanching, which were lower than the control (pH 6.28). The pH value of every molded rice tofu after salting in this study was all lower because the coagulant of rice tofu was GDL. In color respect, the mean b values of all rice tofu trials were higher than those of the control. After forming molded rice tofu, the L value of each formula was increased because of white mycelium. After molded rice tofu was salted, mycelium on the sample was constricted because of salting and formed a mycelium cap. The L value of each formula molded rice tofu after salting was decreased 6~11% while the a and b values significantly increased. The result of texture profile analysis revealed that the values of hardness and springiness in molded rice tofu after blanching with 15% addition of indica rice flour were the highest, which were 2.69N and 8.93mm, respectively. The value of adhesiveness in molded rice tofu after blanching with 15% addition of cassava starch was the highest, which was 2.75mJ. Blanching procedure would retard the decomposition of molded rice tofu. The results of the objective evaluation showed that the data of hardness, chewiness and adhesiveness were in accordance with texture profile analysis. Molded rice tofu after blanching of very acceptable quality could be produced adding 9% indica rice flour and 6% cassava starch.
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